idle surge? Im out of options!

[CleenGST]

Ok so i finally got the kinks worked out of my 6bolt swap. now when i start it, it will rev pretty high, then idle surge from 2000-2400 then work its way down to 1000-1500 but if i tap the gas it will goto 4000'ish and hold there

is this typical of idle surge? what should i do? buy a new isc? please help im lost i want to drive my car

 

[Dsm2nr89]

Heh i have a smiliar problem on my 91 tsi awd ,only mine doesnt stay at 4k rpm after revving it when rpm's drop.Id say replace your thermostat if you haven't already done so.If the problem still persists,then get a new isc.

 

[CleenGST]

the motor is a brand new 6bolt in my 98 gst. now it is working fine just surging from 1000-1300. so i dont know what it is

 

[Dsm2nr89]

Make sure the gas tank is clean and the fuel lines and tank free of dirt

 

[JayRolla]

Idle surge. Go through the basics first. Running rich at idle can cause it. Boost leaks behind the throttle body can cause it so do a boost leak test. A bad FIAV can cause it. Do this and you should fix it.

http://vfaq.com/index-main.html

 

[RedTurboEclipse]

make sure throttle cable is not getting stuck.